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Abstract
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We read with great interest the Article by Birgitte Klee Burton and colleagues in The Lancet Psychiatry assessing motor development and its association with psychotic experiences in children with familial high risk of schizophrenia or bipolar disorder compared with controls. This was one of the largest follow-up studies assessing motor function deficit and other domains in children with familial high risk of schizophrenia or bipolar disorder to date. We commend the authors for the study, but we would like to discuss several aspects of the study design that could have influenced the study findings.
First, the group of children at familial high risk of schizophrenia was matched with children who had no biological parent diagnosed with a schizophrenia spectrum disorder or bipolar disorder. Although the matching considered demographic status, it did not consider socioeconomic status in view of its intrinsic association with high-risk status and to avoid overcorrection. However, it has been observed that individual as well community-level socioeconomic status at the time of birth is associated with an increased risk of schizophrenia. Moreover, matching by education status was also not considered; education status can affect the various motor coordination learning skills and could therefore have influenced the study results.
Second, at both baseline and follow-up, neurological soft sign assessment (beyond motor assessment) was not done, yet there is evidence that people with more neurological soft signs can have an elevated chance of having psychotic experiences and poor performance on motor tasks. Third, it is unclear whether the person who assessed the motor deficit on the Movement Assessment Battery for Children--Second Edition (known as Movement ABC-2) scale was the same or different at baseline and at follow-up; this could lead to an investigator or inter-rater bias, respectively. Fourth, although inclusion criteria were specified in the study, exclusion criteria were not defined; other comorbidities might have been present in these children, which could have affected the outcome...
Language: en |